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Middle and eastern routes of the South-North Water Diversion Project (SNWDP) of China, which are approximately located within the area 28°-42°N and 110°-122°E, are being constructed. This paper investigates the past climatic variations on various time scales using instrumental and proxy data. It is found that annual mean surface air temperature has increased significantly during the past 50-100 years, and winter and spring temperatures in the northern part of the region have undergone the most significant changes. A much more significant increase occurs for annual mean minimum temperature and extreme low temperature than for annual mean maximum temperature and extreme high temperature. No significant trend in annual precipitation is found for the region as a whole for the last 50 and 100 years, although obvious decadal and spatial variation is detectable. A seesaw pattern of annual and summer precipitation variability between the north and the south of the region is evident. Over the last 100 years, the Haihe River basin has witnessed a significant negative trend of annual precipitation, but no similar trend is detected for the Yangtze and Huaihe River basins. Pan evaporation has significantly decreased since the mid-1960s in the region in spite of the fact that the trend appears to have ended in the early 1990s. The negative trend of pan evaporation is very significant in the plain area between the Yangtze and Yellow Rivers. There was a notable series of dry intervals lasting decades in the north of the region. The northern drought of the past 30 years is not the most severe in view of the past 500 years; however, the southern drought during the period from the 1960s to the 1980s may have been unprecedented. The dryness-wetness index (DWI) shows significant oscillations with periodicities of 9.5 and 20 years in the south and 10.5 and 25 years in the north. Longer periodicities in the DWI series include 160-170- and 70-80-yr oscillations in the north, and 100-150-yr oscillations in the south. The observed climate change could have implications for the construction and management of the SNWDP. The official approval and start of the hydro project was catalyzed by the severe multiyear drought of 1997-2003 in the north, and the operation and management of the project in the future will also be influenced by climate change-in particular by precipitation variability. This paper provides a preliminary discussion of the potential implications of observed climate change for the SNWDP. [ABSTRACT FROM AUTHOR]

Abstract: Precipitation is one of the most important elements of the hydrological cycle, and extreme events associated with precipitation are considered a key factor in several types of human activities, including agriculture, for instance. Therefore, the main objective of this paper is to evaluate extreme precipitation indices for the past century, and to analyse the possible tendency of future precipitation conditions for this century for the Carpathian Basin. Several climate extreme indices have been analysed according to the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group (formed at the end of the 1990s) on climate change detection. These precipitation indices include the number of wet days using several threshold values, e.g., 20mm (RR20), 10mm (RR10), 5mm (RR5), 1mm (RR1), 0.1mm (RR0.1), the upper quartile and the 95th percentile of daily precipitation in the base-period 1961–1990 (R75 and R95); the maximum number of consecutive dry days (CDD); the highest 1-day precipitation amount (Rx1); the greatest 5-day rainfall total (Rx5); the annual fraction due to extreme precipitation events (R95T); simple daily intensity index (SDII), etc. Our results suggest that regional intensity and frequency of extreme precipitation increased in the Carpathian Basin during the second half of the 20th century, while the total precipitation decreased and the mean climate became slightly drier during the whole 20th century. In the second part of this paper, several IPCC emission scenarios have been compared and GCM outputs have been analysed in order to project precipitation conditions in the Carpathian Basin for the 21st century. These climate simulations suggest that climate of this region may become drier in summer and wetter in winter, which highlight the importance of hydrological and agricultural planning in Hungary. [Copyright &y& Elsevier]